Method of and apparatus for attaching flexible retaining margins to artificial dentures



G FLEXIBLE ENTURES May 15, 1928.

F. W. BARBOUR METHOD OF AND APPARATUS FOR ATTAC RETAINING MARGINS TO ARTIFICIA Filed April '7, 1927 INVENTDH. 072% a, 4

Patented May 15, 1928.

UNITED STATES 1,669,732 PATENT OFFICE.

FRED W. BARBOUR, OF TORONTO, ONTARIO, CANADA.

METHOD or AND APPARATUS FOR ATTACHING FLEXIBLE RETAINING MARGINS T0 ARTIFICIAL DENTURES.

Application filed April 7, 1927. Serial No. 181,831

This invention relates to denture plates and more particularly to the type having a rim or flexible margin of soft rubber for forming a cushion against the gum and my object is to provide a denture of this character in which the flexible margin is so connected as to remain permanently in place when in use and to devise a method for producing this result.

I attain my object by forming a slight recess around a model with its outer edge at the desired periphery of the finished denture; putting the teeth on the model by means of wax and removing the wax with the teeth from the model for fitting them in the patients mouth; turning or cutting down the .wax' completely around the outside edge thereby providing clearance sufficient for attaching a groove-former to the model; attaching the groove former which is positioned by the hereinbefore mentioned recess in the model; filling in the clearance space with wax havingits outer"'surface determined by a bead on the groove former; investing the model in the lower half of flask which is filled up to a laterally extending flange on which the bead of the groove former is carried; completing the investment; warming the flask and then separatin it; pulling out the groove-former from the lower half of flask; washing away the wax from around the teeth which are now imbedded in the upper half of the flask;

vulcanite rubber in the remainder of the groove on the outer side of the flexible m'argin and around the teeth on the other half of the flask; applying pressure to the flask thereb bringing its parts into perfect relationship for forming the vulcanite plate; vulcanizing the vulcanite rubber into a plate and on to the flexible margin; and then finishing in the usual manner. 'The construction of the parts and the method of procedure are hereinafter more fully described and illustrated in the'accompanying drawings in which I Fig. 1 is a cross section of the impression material and its tray;

Fig. 2 a cross section, partly in elevation, of a model made from the impression material and showing the pencil mark for defining the exact area that the proposed denture will cover;

' Fig. 3 a frontelevation, partly in section, of the model showing a second line drawn about below the first line, the space between the lines being darkened and showing the groove formed round the darkened area in the sectional part of the view;

Fig. 4 a sectional view of part of the model showing the teeth fitted thereto and showing the wax cut back to provide clearance for the attachment of the groove-form- Fig. 5 a perspective view of'a piece of the groove-former;

Fig. 6 a sectional View of part of the model showing the groove-former in position, the space between the wax on the teeth and the groove-former being filled with wax;

Fig. 7 a cross section of a flask showing the model invested and the upper half filled with plaster to complete the investment;

Fig. 8 a detail in cross section showing the groove-former removed from the lower half of the flask and the groove formed therein;

Fig. 9 a perspective detail of a piece of flexible margin;

Fig. 10 a detail in cross section showing the flexible margin in position in the groove;

Fig. 11 a detail in plan of Fig. 10 showing how the flexible margin may be slitted for fitting it around sharp curves in the groove; Fig. 12 a side elevation of the nished denture; and:

Fig. 13 a cross section of a non-palatal or roofless denture.

In the drawings like numerals of reference indicate corresponding parts in the different figures.

l is the impression material carried on'a tray 2 and shaped, in the usual manner, by insertion in the patients mouth. From this impression is made a model 3, preferably of plaster Paris, in the ordinary manner. A pencil line 4: is then drawn around the model to define the exact area that the proposed denture will cover, care being taken to avoid anyplaces which would mean a danger of marginal irritation (see Fig. About within the first line 4 and parallel thereto is drawn a second line 4 and i the area between the lines 4 and 4 is filled in preferably by means of a coloring fluid, such as ink, to form a dark band f around the model. The outside edge 4 of the band is the exact outside or periphery of the proposed denture. Any suitable tool is then used to form a concave recess in the model around the darkened band 4". Preferably a small wooden wheel having its periphery curved in cross section is used for the urose of grinding the recess 5 which is a out in depth and the full width of the colored band, as shown in Fig. 3. at certain regions in which the ridge tissue only slightly compressible, the recess may be made shallower. The coloring on the model serves to soften the plaster to facilitate the forming of the recess, gives an easily dlscernible area to work on, and furthermore as it is being ground the color changes and thus removes the possibility of missing any portion.

The surplus part of the model is then trimmed down with the edge thereof bevelled off from a line at or adjacent the upper ed e of the recess 5.

f it is desired to fit the teeth before completing the denture, they will be put on the model 3 by means of wax 7 in the usual way and then the wax with the teeth imbedded therein will be removed from the model to fit them in the patients mouth. The wax and the teeth thereon will next be placed back on the model and the wax will be cut back about A from the recess 5, as indicated at 7 a in Figs. 4 and 6. One purpose of this recess 5 is to position correctly a grooveformer 6 which is formed of a strip of material substantially L shaped in cross section. One flange 6 of this strip is smooth and has a rounded edge which is fitted into the recess 5 with the smooth flange extending a slight distance upon the side of the model. The groove-former material is such that a strip thereof may be readily bent up, down, in or out without cracking to follow the recess 5 while retaining its cross sectional contours. If necessary the laterally extending flange 6 of the groove-former may be slitted to enable the rounded edge to remain in the recess 5 at curves of short radii. Any suitable material, such as wax, may be used to attach the groove-former in position on the model. The next step is to fill wax 8 into the space between the surface 7 a of the wax 7 and the flange 6" of the groove-former 6, as shown in Fig. 6. The laterally extending flange 6 is provided with a bead 6 which is substantially parallel to the flange 6 but extends from the flange 6 in a direction opposite to that of the flan e 6. The bead determines the thickness of t e wax 8 around the model and also serves to distinguish one flange from the other to ensure the proper flange being inserted on the recess 5. A fnr-,

ther distinction is made by forming the free edge of the flange 6 as a right angled corner while the free edge of the flange 6 is rounded as hereinbefore mentioned.

If it is not desirable to fit the teeth in the patients mouth before completing the denture, the groove-former 6 will be attached to the model, in the hereinbefore described manner, before the teeth with their wax carrier 7 are attached thereto. This saves the cutting back or trimming of the wax 7 and the adding of the wax 8 as the wax 7 may be continued along the side of the model and into contact with the flange 6" and the bead 6.

The model is next invested in the lower half 9 of a flask which is filled in with the usual investment material 12 having its upper surface extending substantially from the rim of the flask to the upper edge of the bead 6. The highest point of the latter should not be above the upper edge of the flask rim. The investment of the upper half 9 of the flask is done in the usual manner and the teeth are imbedded in this half of the flask as usual.

The flask is then warmed and the halves 9 and 9 are separated from one another to permit the groove-former 6 to be removed from the groove 10.

The wax 7 and 8 from around the teeth, which are now imbedded in the upper half of the flask, is now washed out in the usual manner. Ordinary vents are formed for surplus vulcanite but these must be made in the upper half of the flask otherwise the sides of the groove 10 would be damaged.

A flexible margin 11 is formed of a strip of soft rubber having a concaved surface 11, a lower rounded edge l1 which terminates in a shoulder 11 on the outer side of the strip, and a thin end 11 which tapers convexly from the shoulder to the upper end of the concaved surface. The junction of the convexed and the concaved surfaces is substantially a feather edge. The flexible margin is inserted in the groove 10 with the rounded end 11 in contact with the bottom of the groove and the concaved surface 11 in contact with the inner side thereof (see Figs. 9 and 10). In other words, the rounded edge 11 of the rubber strip is positioned in that portion of the groove 10 that was originally formed by the recess 5 in the model whereby the said rounded edge will engage the ridge in the patients mouth. The cross-sectional shape of the flexible margin is such that the concaved side thereof tends to fit snugly against the inner side of the groove 10 which is the outer side of the model. Slits may be cut into the thin end 11 of the flexible margin at any place where it does not fit snugly against the inner wall of the groove 10. The slits will tend to eliminate puckering and will tend to im- 'prove the fit around sharp curves.

Any spaces may be filled in with, and the butted ends of the strip joined together by, small pieces of the soft rubber or a rubber liquid or cement having the same ingredients as the flexible margin. The preferred arrangement is to dip the small pieces into the cement and then place them in the spaces.

The remainder of the groove 10 may then be filled in with vulcanite rubber which may be added also to cover the exposed surface of the model 3 in the lower flask 9. Care must be taken to see that this 'ulcanizing rubber engages only the side of the groove remote from the concaved side of the flexible margin. The upper side of the flask is packed with sutlicient vulcanite rubber to ensure an oversupply as usual.

The halves 9 and 9 of the flask are then connected together as usual and are caused. by sutficient pressure to forcethe flexible margin firmly against the model to avoid the danger of the vulcanite rubber creeping in between them. The flask is then heated and more pressure applied to bring the flask halves to their proper relationship and thus the surplus is extruded through'the vents. The vulcanizing process is then done as usual but it is preferred that the temperature be kept at 300 for two and one-half hours. The denture is then finished in the usual manner.

In the above described process the polishing and varnishing operations which are well known in' the art have not been mentioned.

While the drawings and description relate only to a complete upper denture with the major portion of the hard palate it is obvious that this portion may be omitted and the flexible margin on the plate be brought round as indicated in dotted lines in Fig. 12 and in section in Fig. 13 for engaging the inner sides of the ridgesinstead of the way it is shown in full lines for engagement with the roof of the mouth. This forms a denture of the so-called roofless type or a full lower denture. It is also obvious that the flexible margin may be used on partial dentures, particularly Class I and Class II (including modifications) and also for full uppers already in service and which lack suflicient retention. 1

What I claim is:

1. The method of forming a denture which consists in forming a model, attaching a groov eformer around the modelwith its outer edge defining the exact area the proposed denture will cover, investing the model in one half of a flask, completing the investment and forming the mold cavity. removing the groove former from its flask half, inserting a flexible margin into the groove formed around the model, packing vulcanite rubber in the flask so that it will contact with the flexible margin, and vulcanrecess defining the exact area the proposed denturewill cover, attaching a groove-former around the model with its outer edge inserted in the recess, investing the model in one half of a flask, completing the investment and forming the mold cavity. removing the groove former from its flask half. inserting a flexible margin into the groove formed around the model, packing vulcanite rubber in the flask so that itwill contact with the flexible margin, and vulcanizing the vulcanite rubber to the flexible margin.

3. The method of forming a denture which consists in forming a model, attaching a groove former around the model with its outer edge defining the. exact area the proposed denture will cover, investing the model in one half of a flask, applying wax for placing the teeth on the model, the groove former being so shaped that. it determines the thickness ofthe wax around the model, completing the investment, separating the halves of the flask, removing the wax and the groove-former, inserting a flexible margin into the groove formed around the model. packing vulcanite rubber in the flask so that it will contact with the flexible margin, and vulcanizing the vulcaniterubber to the flexible margin.

4. The method of forming a denture which consists in forming a model, drawing with coloring fluid a narrow band around the model, the outer edge of the band being the exact outside or periphery of the pro posed denture, forming a slight concaved recess around the model along the colored band, applying wax for placing the teeth on the model, removing the wax and the teeth for fitting them in the patients mouth, replacing the teeth and wax on the model, cutting back the wax'from the recess, attaching a groove-former'around the model with its outer edge inserted in the recess, filling in with wax the space between the groove-former and the wax on which the teeth are carried, investing the ,model in one half of a flask, completing the investment, warming the flask and then separating it, pulling out the groove former, washing away the wax, venting the half of the flask in which the teeth are now imbedded, inserting a flexible margin of soft rubber in the groove formed by the groove-former around the model, the flexible margin being formed of a strip so shaped in cross section that it tends to fit snugly around the model and its outer edge fills the bottom of the groove and tends to fit snugly in the said recess, the groove former being so shaped that it will model, packing vulcanite rubber in the flask so that it will overlie a portion of the outer side of the flexible margin, and vulcanizing the vulcanite rubber to the flexible marm.

a 5. The method of forming a denture which consists in forming a model, drawing a line around the model for defining the ex act area the proposed denture will cover, drawing a second line slightly spaced vfrom and substantially parallel to the first line, the second line being within the area of the proposed denture, drawing with coloring fluid a narrow band between the said lines, forming a slight concaved recess around the model along the colored band, applying wax for placing the teeth on the model, removing the wax and the teeth for fitting them in the patients mouth, replacin the teeth and wax on the model, cutting bac the wax from the recess, attaching a groove-former around the model with its outer edge inserted in the recess, filling in with wax the space between the groove-former and the wax on which the teeth are carried, investing the model in one half of a flask, completing the investment, warming the flask and then separating it. pulling out the groove former, washing away the wax, venting the half of the flask in which the teeth are now imbedded, inserting a flexible margin of soft rubber in the groove formed by the groove-former around the model, the flexible margin being formed of a strip so shaped in cross section that it tends to fit snugly around the model and its outer edge fills the bottom of the groove and tends to fit snugly in the said recess, the groove former being so shaped that it will ensure an even thickness of wax around the model, packing vulcanite rubber in the flask so that it will overlie a portion of the outer side of the flexible margin, and vulcanizing the vulcanite rubber to the flexible margin.

ensure an even thickness of wax around the 6. In a method of forming a denture with a flexible margin around its periphery, the steps which consist in forming around a model a recess with its outer edge defining the exact area the proposed denture will cover, attaching a groove-former of material adapted to be bent to shape longitudinally while retaining its cross sectional contours and positioned by said recess for forming in an investment a groove adapted to receive the flexible margin, investing a model, removing the groove-former, and inserting the flexible margin in the groove in close engagement with the recess.

7. Apparatus for forming an artificial denture comprising a model having a recess formed around it, and a groove-former adapted to be partly received in the recess formed of a strip of material adapted to be bent to shape longitudinally while retaining its cross sectional contours.

8. Apparatus for forming an artificial denture comprising a model having a recess formed around it, and a grooveiormer formed of material substantially L shaped in cross section adapted to be bent to shape longitudinally while retaining its cross-sectional contours and having one flange positioned by the said recess.

9. Apparatus for forming an artificial denture comprising a model having a recess formed around it, and a groove-former formed of material substantially L shaped in cross section adapted to be bent to shape longitudinally while retaining its cross-sectional contours and having one flange positioned by the said recess, the other flange of the groove-former being provided with a bead directed substantially parallel to the first mentioned flange but extended from the secand mentioned flange in a direction opposite to that of the first mentioned flange.

Signed at Toronto, Canada, this 21st day of March, 1927.

FRED W. BARBOUR. 

